There is conventionally known a sheet feeder provided with a mechanism for separating one sheet from a plurality of stacked sheets and conveying the separated sheet. This conventional sheet feeder includes a first roller, a second roller, and a pick arm. The first roller conveys a plurality of sheets stacked on a shooter downstream in a conveying direction. The second roller restrains sheets other than the bottommost sheet from being conveyed downstream.
The pick arm can move in a direction toward the first roller and a direction away from the first roller. The pick arm rotatably supports a third roller and a flap at a portion of the pick arm positioned nearest the first roller. A spring urges the flap to rotate in a first direction. When the pick arm is moved toward the first roller, the third roller contacts the topmost sheet, and the flap is inserted into a conveying path at a position downstream of the plurality of sheets. When the plurality of sheets is conveyed downstream, the sheets push the flap downstream, causing the flap to rotate in a second direction opposite the first direction so as to be retracted from the conveying path.